The swine melanoma tumor system is an animal model of spontaneous malignant disease that has many features in common with its human counterpart. Features of this tumor system include a histopathologic resemblance to human superficial spreading melanoma, a high incidence of primary cutaneous melanomas, a high incidence of benign melanocytic lesions that transform to malignant melanoma, and the occurrence of metastatic disease. The objective of this project is to isolate and partially purify melanoma-associated antigen(s) from primary cutaneous melanomas and metastatic lesions and to compare these antigens with similarly isolated fractions from benign melanocytic lesions and normal black swine skin. Two approaches will be used to isolate antigenic fractions from 3M KCl tumor extracts. A biochemic approach will utilize a combination of techniques including gradient density centrifugation, polyacrylimide gel electrophoresis, and anion exchange chromatography. An immunologic approach will utilize affinity chromatography techniques both to remove normal tissue antigens and to isolate melanoma-associated antigen(s) from tumor extracts. Fractions from various tumors and different tumor types will be evaluated for melanoma-associated antigen activity and immunologic cross-reactivity. Thus, this unique animal model provides the opportunity to evaluate the relationship between melanoma-associated antigens and the cellular events associated with neoplastic transformation and progressive or regressive growth.